Macro- and Micro- Organism Study at Sand Island Intertidal
Mari Taira, Farrington High School
During the Spring of 2008, Marine Science students were involved in an intertidal
investigation at Sand Island. Throughout the semester students have studied different
components of ecosystems with a unit focused on the producers in the ocean, the
microorganisms phytoplankton and cyanobacteria and also the macroalgae, seaweed.
During class students observed plankton samples collected from two different
sites, Mokauea Island off of Sand Island and Kaneohe Bay. Students compared the two
samples and identified both zooplankton and phytoplankton using a picture identification
guide. As a class we discussed the importance of microorganisms in the food chain and
in oxygen production in marine ecosystems. Students studied the field of microbial
oceanography by rotating through labs to watch scientists on the HOT cruise gather their
samples and use the most recent technology. Students also did their own interactive
investigations using the CD-ROM “Phytopia” on
laptops.
These in class labs and activities helped to
prepare the students for their field work and further
experiments on the marine organisms at Sand Island.
Although student’s experiments focused on
distribution and the macrofauna in the intertidal
zone, we incorporated the study of microorganisms
by filtering seawater collected from their site. This
microorganism lab would be a class experiment, as
groups worked on their own investigations.
At the end of the field trip students collected
water that was brought back to the class and
refrigerated to preserve the microorganisms. During
class a few students worked to set up the vacuum and
filtering equipment for the class demonstration.
Students used this class experiment as an opportunity
to practice writing detailed methods for their own
investigation. Once the vacuum, filter, and
microscopes were set up a demonstration was given
to the class. Groups rotated to the lab and filtered
their Sand Island seawater with two different sizes of filters. Students then identified
their organisms using the guides provided. Their observations showed various planktonic
invertebrate larvae and a few phytoplankton samples.
Students added their findings from this lab
to previous lessons on microorganisms and
incorporated knowledge into their intertidal lab
introduction. Many students focused on marine
organisms that depend on plankton for food or that
have planktonic larvae. The inclusion of these
activities seemed very meaningful for the students.
Based on student reflections, they seemed to gain a
better understanding of the importance of
microorganisms that sustain the food webs in the
ocean and the oxygen on Earth.